An extremely low loss circle-based star shape photonic crystal fiber (CS-PCF) has been proposed for terahertz (THz) spectrum. A dielectric material TOPAS has been used for constructing the proposed model. Some important parameters for the proposed waveguide have been investigated a wide THz spectrum ranging from 0.5 to 2.50 THz. The simulation result exhibits an extremely-low material loss of 0.01607 cm−1 and a large effective area of 1.386 $\times$ 106 $\mu$m2 at 1.0 THz frequency with 55% core porosity. In addition, the proposed structure establishes comparatively higher core power fraction maintaining lower scattering loss about 1.235 $\times$ 10−15 dB/cm and 91.97% of bulk absorption material loss at the same operating frequency. From the above results, it is anticipated that proposed CS-PCF model of the THz waveguide will make the conventional communication very effective over the current designs.